 Figure 10c: (a) A 1-mm transverse CT image through the right midlung shows a 10-mm pure ground-glass nodule (arrow). (b) CT image in the same location as a at 15-month follow-up shows only a very subtle increase in opacity. (c) CT image in the same location as a and b a further 10 months after b shows the nodule has evolved into a larger part-solid nodule. Surgical resection revealed stage 1A invasive lepidic predominant adenocarcinoma. Further evidence in support of conservative monitoring of these lesions has been provided recently by Yankelevitz et al (34), who described a large-scale screening study in which 2392 (4.2%) pure ground-glass (nonsolid) nodules were identified among 57 496 baseline studies. From these, a total of 73 lesions subsequently proved to be adenocarcinomas. Overall median time to treatment was 19 months, with solid components developing in 19 (26%) malignant nodules within a median time of 25 months. These all proved to be stage 1 lesions, with an overall survival rate of 100%. Although these reports represent strong evidence for a conservative approach to pure ground-glass lesions, initial follow-up at 6 months is still recommended, particularly in those nodules with features reported to be risk factors for progression. These include larger lesion size, especially diameter greater than 10 mm (7,35–38), and the presence of bubbly lucencies (35,37,39,40). Of particular concern are patients who are uncomfortable with the prospect of waiting 12 months for follow-up examinations. In this setting, sooner follow-up may be warranted, as many of these lesions will either resolve or show no change, thereby reassuring the patient (Fig 11 |